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SubjectRe: [PATCH] scsi: libsas: Fix exp-attached end device cannot be scanned in again after probe failed
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Hi Jason,

On 2024/4/18 9:46, Jason Yan wrote:
> On 2024/4/17 15:47, yangxingui wrote:
>>
>>
>> On 2024/4/17 9:46, Jason Yan wrote:
>>> Hi Xingui,
>>>
>>> On 2024/4/16 11:07, Xingui Yang wrote:
>>>> We found that it is judged as broadcast flutter and exits directly
>>>> when the
>>>> exp-attached end device reconnects after the end device probe failed.
>>>
>>> Can you please describe how to reproduce this issue in detail?
>> The test steps we currently construct are to simulate link
>> abnormalities and adjust the rate of the remote phy when running IO on
>> all disks.
>>
>> When the sata disk is probed and the IDENTIFY command is sent to the
>> disk, the expander return rate is abnormal, causing sata disk probe
>> fail. But there may be many reasons for device probe failure,
>> including expander or disk instability or link abnormalities.
>>
>>>
>>> Thanks,
>>> Jason
>>>
>>>>
>>>> [78779.654026] sas: broadcast received: 0
>>>> [78779.654037] sas: REVALIDATING DOMAIN on port 0, pid:10
>>>> [78779.654680] sas: ex 500e004aaaaaaa1f phy05 change count has changed
>>>> [78779.662977] sas: ex 500e004aaaaaaa1f phy05 originated
>>>> BROADCAST(CHANGE)
>>>> [78779.662986] sas: ex 500e004aaaaaaa1f phy05 new device attached
>>>> [78779.663079] sas: ex 500e004aaaaaaa1f phy05:U:8 attached:
>>>> 500e004aaaaaaa05 (stp)
>>>> [78779.693542] hisi_sas_v3_hw 0000:b4:02.0: dev[16:5] found
>>>> [78779.701155] sas: done REVALIDATING DOMAIN on port 0, pid:10, res 0x0
>>>> [78779.707864] sas: Enter sas_scsi_recover_host busy: 0 failed: 0
>>>> ...
>>>> [78835.161307] sas: --- Exit sas_scsi_recover_host: busy: 0 failed:
>>>> 0 tries: 1
>>>> [78835.171344] sas: sas_probe_sata: for exp-attached device
>>>> 500e004aaaaaaa05 returned -19
>>>> [78835.180879] hisi_sas_v3_hw 0000:b4:02.0: dev[16:5] is gone
>>>> [78835.187487] sas: broadcast received: 0
>>>> [78835.187504] sas: REVALIDATING DOMAIN on port 0, pid:10
>>>> [78835.188263] sas: ex 500e004aaaaaaa1f phy05 change count has changed
>>>> [78835.195870] sas: ex 500e004aaaaaaa1f phy05 originated
>>>> BROADCAST(CHANGE)
>>>> [78835.195875] sas: ex 500e004aaaaaaa1f rediscovering phy05
>>>> [78835.196022] sas: ex 500e004aaaaaaa1f phy05:U:A attached:
>>>> 500e004aaaaaaa05 (stp)
>>>> [78835.196026] sas: ex 500e004aaaaaaa1f phy05 broadcast flutter
>>>> [78835.197615] sas: done REVALIDATING DOMAIN on port 0, pid:10, res 0x0
>>>>
>>>> The cause of the problem is that the related ex_phy information was not
>>>> cleared after the end device probe failed. In order to solve the above
>>>> problem, a function sas_ex_unregister_end_dev() is defined to clear the
>>>> ex_phy information and unregister the end device when the
>>>> exp-attached end
>>>> device probe failed.
>>>>
>>>> As the sata device is an asynchronous probe, the sata device may probe
>>>> failed after done REVALIDATING DOMAIN. Then after the port is added
>>>> to the
>>>> sas_port_del_list, the port will not be deleted until the end of the
>>>> next
>>>> REVALIDATING DOMAIN and sas_destruct_ports() is called. A warning about
>>>> creating a duplicate port will occur in the new REVALIDATING DOMAIN
>>>> when
>>>> the end device reconnects. Therefore, the previous destroy_list and
>>>> sas_port_del_list should be handled before REVALIDATING DOMAIN.
>>>>
>>>> Signed-off-by: Xingui Yang <yangxingui@huawei.com>
>>>> ---
>>>>   drivers/scsi/libsas/sas_discover.c |  2 ++
>>>>   drivers/scsi/libsas/sas_expander.c | 16 ++++++++++++++++
>>>>   drivers/scsi/libsas/sas_internal.h |  6 +++++-
>>>>   3 files changed, 23 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/scsi/libsas/sas_discover.c
>>>> b/drivers/scsi/libsas/sas_discover.c
>>>> index 8fb7c41c0962..aae90153f4c6 100644
>>>> --- a/drivers/scsi/libsas/sas_discover.c
>>>> +++ b/drivers/scsi/libsas/sas_discover.c
>>>> @@ -517,6 +517,8 @@ static void sas_revalidate_domain(struct
>>>> work_struct *work)
>>>>       struct sas_ha_struct *ha = port->ha;
>>>>       struct domain_device *ddev = port->port_dev;
>>>> +    sas_destruct_devices(port);
>>>> +    sas_destruct_ports(port);
>>>>       /* prevent revalidation from finding sata links in recovery */
>>>>       mutex_lock(&ha->disco_mutex);
>>>>       if (test_bit(SAS_HA_ATA_EH_ACTIVE, &ha->state)) {
>>>> diff --git a/drivers/scsi/libsas/sas_expander.c
>>>> b/drivers/scsi/libsas/sas_expander.c
>>>> index f6e6db8b8aba..6ae1f4aaaf61 100644
>>>> --- a/drivers/scsi/libsas/sas_expander.c
>>>> +++ b/drivers/scsi/libsas/sas_expander.c
>>>> @@ -1856,6 +1856,22 @@ static void
>>>> sas_unregister_devs_sas_addr(struct domain_device *parent,
>>>>       }
>>>>   }
>>>> +void sas_ex_unregister_end_dev(struct domain_device *dev)
>>>> +{
>>>> +    struct domain_device *parent = dev->parent;
>>>> +    struct expander_device *parent_ex = &parent->ex_dev;
>>>> +    int i;
>>>> +
>>>> +    for (i = 0; i < parent_ex->num_phys; i++) {
>>>> +        struct ex_phy *phy = &parent_ex->ex_phy[i];
>>>> +
>>>> +        if (sas_phy_match_dev_addr(dev, phy)) {
>>>> +            sas_unregister_devs_sas_addr(parent, i, true);
>>>> +            break;
>>>> +        }
>>>> +    }
>>>
>>> Did you mean this end device is a wide-port end device ? How could
>>> this happen?
>>
>> No, the end device described here is a non-expander device. Such as:
>> sata/sas disk. But these devices are exp-attached.
>
> If it is not a wide port, why do they have the same sas address here?
> Why do you add this function to unregister these PHYs? And the last
> parameter of sas_unregister_devs_sas_addr() means the last PHY of the
> wide port, you just all passed true, it is irrational.
The non-expander end device does not have a wide port, such as a sata
disk, and there is only one ex_phy corresponding to it. This function
finds the ex_phy corresponding to the end dev through dev->sas_addr,
then clears the ex_phy information and unregister the end device.

Thanks,
Xingui

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